1. Field of the Invention
The present invention relates to a method for controlling semiconductor fabrication equipment and, more particularly, to a method for simultaneously and automatically controlling semiconductor fabrication equipment and a computer system such as a host computer.
2. Background of the Related Art
Semiconductor device fabrication includes a large number of processes, requiring a large amount of equipment (i.e., sputtering equipment, deposition equipment, etching equipment, etc.) to be disposed on a fabrication line. Within this equipment, wafers grouped as unit lots of approximately 20 to 25 wafers are processed under optimal conditions for the respective steps of the process.
If the equipment performs the process according to an offline technology, data generated during the respective steps are displayed on the monitor of the equipment. If the equipment performs the process according to an online technology, the data are stored in the data base of a host computer connected to the equipment.
FIG. 1 is a flowchart illustrating a conventional method for controlling semiconductor fabrication equipment. In the method, a determination as to whether the process is performed under the optimal process conditions for the respective steps is made through a measuring step after several steps are performed as shown in FIG. 1. At the measuring step, it is determined whether or not the products processed through the several steps are defective. If it is determined that the products are defective at the measuring step, the result is displayed on the monitor of the equipment which performs the process, or the causes of the defects are detected using data stored in the data base of the host computer.
In other words, in the event that the process is performed under poor conditions, the determination as to whether or not the products are defective cannot be made immediately after one step is completed. Moreover, in the event that the defects in the products are detected at the measuring step after several process steps are carried out, the process steps are traced back so as to detect the causes of the defects. This may result in loss of time and material.
Such poor process conditions may occur when the process condition for a certain step has not been set to its optimal condition due to an error on the part of an engineer, when lots are continuously processed under a condition wherein process condition input was improper, or when a process is continuously performed under a condition wherein process ambient has not been set to its optimal condition due to operation failure of the equipment itself.
Accordingly, a method for equipment control is used, which method is capable of suppressing the poor condition associated with the above cases. In the method, data generated in the equipment are compared with specification values which are initially registered in the data base of the host computer. If the equipment-generated data are not in the range of the specification values, the equipment is switched to an interlocked state.
However, the method suffers from several disadvantages. When the fabrication equipment is controlled according to the method, only the equipment is interlocked and the information on the interlocked equipment (for example, the intrinsic number of the interlocked equipment) is not saved in the host computer. Thus, the actual state of the interlocked equipment is different from the state thereof recognized by the host computer. Accordingly, the host computer cannot identify the interlocked equipment.
Generally, when equipment is interlocked, an alarm signal is generated in an alarm device installed on the equipment. According to the alarm signal, the operator informs the engineer that the equipment is interlocked by means of a communication device such as a telephone. The engineer then takes appropriate action on the interlocked equipment to solve the problem thereof and informs the operator that the problem of the equipment has been solved. Then, the operator releases the interlocked state of the equipment and returns the equipment to the fabrication process. In this method, the operator must check every piece of equipment, without omission, in order to determine whether or not the equipment became interlocked during the respective fabrication steps. This work requires a great amount of time and labor. For this reason, the operator actually cannot check all the equipment.
When an operation command is accidently inputted into the host computer by the operator when the problem in the interlocked equipment has not been solved by the engineer, the host computer cannot recognize the fact and the steps of the process are continuously performed by the equipment under an improper set condition. The improperly set condition may result in an increase in defective products and degraded process reliability.